Field of the Invention
The present invention relates to a feeding device configured to convey a sheet of paper (recording medium) one by one and to a recording apparatus that includes the feeding device and is configured to form an image on the sheet.
Description of the Related Art
U.S. Pat. No. 6,880,821 discusses a recording apparatus that includes a feeding device configured to convey a plurality of sheets set in a feed cassette one by one from the feed cassette. This feeding device in the recording apparatus includes a swing arm feed mechanism unit, having a feed roller provided at a leading end thereof, and an inclined separator. The swing arm feed mechanism unit is configured to transmit rotary drive force from a feed roller rotary drive unit (not illustrated) to the feed roller, and the feed roller at the leading end is in contact with the surface of an uppermost one of the sheets set in the feed cassette. Upon receiving the rotary drive force, the feed roller rotates in a direction to convey the sheet toward the inclined separator. The inclined separator includes, on a front surface thereof, a plurality of fixed separation portions and a plurality of movable separation portions, and the movable separation portions are configured to be movable between a contact position and a non-contact position with the sheet by a cam disposed on a rear surface of the inclined separator. This cam is connected to a rotary lever, and rotating this rotary lever allows the positions of the movable separation portions to change.
When the feeding device conveys a sheet having low stiffness, the movable separation portions are moved to the contact position to increase a contact area between the sheet and the inclined separator. Thus, frictional force between the sheet and the inclined separator increases, and the frictional force between the sheet and the inclined separator exceeds frictional force between the sheet and another sheet, which suppresses a double feed of the sheets. In contrast, when the feeding device conveys a sheet having high stiffness, the movable separation portions are moved to the non-contact position to allow the sheet to make contact only with the fixed separation portions, and thus a contact area between the sheet and the inclined separator is decreased. Then, the frictional force between the sheet and the inclined separator decreases, and the sheet is smoothly conveyed along the inclined separator, which suppresses a non-feed of the sheet.
U.S. Pat. No. 7,097,171 discusses a recording apparatus that includes a feeding device configured to convey a plurality of sheets set in a feed cassette one by one from the feed cassette using a belt. This feeding device in the recording apparatus includes a swing arm feed mechanism unit, having a feed roller provided at a leading end thereof, and an inclined separator, on which the belt is provided. The swing arm feed mechanism unit is configured to transmit rotary drive force from a feed roller rotary drive unit (not illustrated) to the feed roller, and the feed roller at the leading end is in contact with the surface of an uppermost one of the sheets set in the feed cassette. Upon receiving the rotary drive force, the feed roller rotates in a direction to convey the sheet toward the inclined separator. The inclined separator includes a plurality of separation portions and the belt for imparting frictional force to the leading end of the sheet.
If the frictional force between the uppermost sheet and the second sheet from the top in the feed cassette is large, when the uppermost sheet is conveyed, the second sheet is likely to be conveyed as well along with the uppermost sheet. However, as the belt makes contact with the second sheet, a double feed of the second sheet is suppressed. The belt rotates in a direction to impart, to the sheet, conveyance force that acts in a direction opposite to that of the feed roller. Thus, even if the uppermost sheet and a sheet immediately underneath the uppermost sheet (the second sheet) are conveyed from the feed cassette to the inclined separator, the frictional force between the belt and the second sheet prevents the second sheet from being conveyed beyond the inclined separator and sends the second sheet back to the feed cassette.
However, as the number of sheets set in the feed cassette decreases, a load of the sheets on the feed cassette decreases as well, and in turn frictional force between the sheets and the feed cassette decreases, which may allow a double feed of sheets to occur more easily. Therefore, it is necessary to impart appropriate frictional force to the sheets to suppress a double feed.
In the recording apparatus discussed in U.S. Pat. No. 6,880,821, the movable separation portions are moved to the contact position to increase the frictional force between the inclined separator and the sheet. However, this increases the frictional force across the entire inclined separator, and thus if only a single sheet is conveyed to the inclined separator, the sheet may not smoothly slide on the inclined separator. Thus, the sheet may slack, and the conveyance of the sheet may in turn be suspended on the surface of the inclined separator, which may result in a non-feed of the sheet.
Similarly, in the recording apparatus discussed in U.S. Pat. No. 7,097,171, the belt is provided over the entire center area of the inclined separator along the conveyance direction of the sheet. Thus, when only a single sheet is conveyed to the inclined separator, the sheet may not smoothly slide on the inclined separator. In addition, the leading end of the sheet may be caught by the belt, and thus the sheet may be damaged and may not be conveyed correctly along the surface of the inclined separator. As a result, the conveyance of the sheet may be suspended, which may result in a non-feed of the sheet.